The authors introduce a novel coding technique which significantly improves the performance of the traditional vector quantisation (VQ) schemes at low bit rates. High interblock correlation in natural images results in a high probability that neighbouring image blocks are mapped to small subsets of the VQ codebook, which contains highly correlated codevectors. If, instead of the whole VQ codebo...

In this paper, we present a novel approach for codebook design using multiobjective genetic optimization. We partition the pattern space into perceptive classes, which are then clustered into hyperspheres based on multiobjective criteria. Multiobjective genetic algorithms perform optimisation on a vector space of objectives and are able to explore the search space for a set of equally viable an...

Most current image and video coding standards use variable length codes to achieve compression, which renders the compressed bitstream very sensitive to channel errors. In this paper, image and video coders based on Pyramid Vector Quantisation (PVQ) and using only fixed length codes are proposed. Still image coders using PVQ in conjunction with DCT and wavelet techniques are described and their...

It is difficult to achieve a good low bit rate image compression performance with traditional block coding schemes such as transform coding and vector quantization, without regard for the human visual perception or signal dependency. These classical block coding schemes are based on minimizing the MSE at a certain rate. This procedure results in more bits being allocated to areas which may not ...

In this paper we present an approach to face and object detection and recognition based on an extension of the contentbased image retrieval method of Lu and Teng (1999). The method applies vector quantisation (VQ) compression to the image stream and uses Mahalonobis weighted Euclidean distance between VQ histograms as the measure of image similarity. This distance measure retains both colour an...

The paper presents a fast codebook training algorithm for vector quantisation. It uses an elimination rule, based on triangular inequality criteria, as well as the partial distortion elimination method, to relieve the computational burden of a conventional codebook training algorithm, including a binary codeword splitting algorithm for the initial codebook and the LBG recursive algorithm. Over ...

Digital image in raw form require a large amount of storage capacity. Due to limited bandwidth and storage capacity, images must be compressed before storing and transmitting. Image compression means reducing the size of the graphics file, without compromising on its quality. This paper entails the survey of various image compression techniques and highlights the important features of each meth...

We describe a novel text compressor which combines Ziv-Lempel compression and arithmetic coding with a form of vector quantisation. The resulting compressor resembles an LZ-77 compressor, but with no explicit phrase lengths or coding for literals. An examination of the limitations on its performance leads to some predictions of the limits of LZ-77 compression in general, showing that the LZ-77 ...

A new kind of feature for colour image retrieval based on DCT-domain vector quantisation (VQ) index histograms (DCTVQIH) is proposed. For each colour image in the database, 12 histograms (four for each colour component) are calculated from 12 DCT-VQ index sequences, respectively. The retrieval simulation results show that, compared with the traditional spatial-domain colour-histogram-based feat...